Lifting jack



April 1934- 'E. w. CONRAD 1,954,558

LIFTING JACK Filed Aug. 23, 1952 2 Sheets-Sheet 1 E. W. CONRAD LIFTING JACK April 10, 1934.

Filed Aug. 25, 1962 2 Sheets-Sheet 62 1 LJ. mao

' Patented Apr. 10, 1934 UNITED STATES PATENT OFFICE LIFTING JACK Earl W. Conrad, Warsaw, Ind.

Application August 23, 1932, Serial No. 630,082

Claims. (01. 254-126) The invention relates to improvements in jacks of the lazy tong type.

The recent changes in automobile construction and in tires have made it impossible or difficult 5 to use the jacks that are on the market because when at their lowest point they are too high to be engaged under the part to be elevated. Hence a jack whose lowest point permits its use in the above cases is most desirable and it is the object of my invention to provide a simple and efficient jack that will overcome the difficulties mentioned.

The invention consists of the novel combination and arrangement of parts hereinafter described and illustrated in the accompanying drawings in which Figure 1 is a side elevational view of the jack in collapsed condition, Fig. 2 a side view of the jack in extended or raised condition, Fig. 3 a cross-section on line 3-3 of Fig. 2, Fig. 4 a fractional view of a modified form of the upper crossing links, Fig. 5 a fractional view of a further modified form of the upper portion of the jack, and Fig. 6 a plan view of the same partly broken away.

In the accompanying drawings 1 is the base preferably having its opposite ends curved or turned upwardly. Four lugs 2, 3, 4, 5 project upwardly from the base, the lugs 2, 3 being transversely spaced and apertured to receive a bolt or rivet 6 and the lugs'4, 5 also being transversely spaced and apertured to receive the bolt or rivet '7. The lugs 4, 5 are spaced transversely to greater extent than the lugs 2, 3. Two links 8 are pivotally eccentrically mounted at one end on the bolt or rivet 6, and two links 9 are pivotally, eccentrically mounted at one end on the bolt or lrivet 7. The mountings of the links are adjacent to the lugs respectively and to the base 1 and the extremities of the links project into the slots or depressions 10 formed in the base 1. The links 9 cross the links 8 respectively and their opposite or upper ends are pivoted to the blocks 11, 12 respectively the block 11 being tapped to receive the screw 13 and the block 12 loosely receiving the screw. One end of thescrew is connected to a fitting 14 adapted to receive a crank of suitable form by which to rotate the screw. A thrust bearing 15 is disposed between the fitting 14 and the block 12. When the screw is rotated the block 11 will travel toward or away from the other block according to the direction of rotation of the screw. A pin 28 prevents movement of the block 12.

Two links 16, 17 are also pivoted to the blocks 11, 12 respectively and cross each other above the screw. They are pivoted together by the bolt 18 at their crossing point, preferably eccentric to their longitudinal axes. Two links similar to the links 16, 17 are similarly mounted on the opposite side of the blocks 11, 12 respectively and are similarly pivoted at their crossing point. The pivot 18 may be common to both sets of links 16, 17. The upper ends of the links 16 are pivoted together at 19 and similarly the upper ends of the links 1'? are pivoted together at 20 and the pivots 19, 20 are eccentric to the longitudinal axes of the links. A support 21, preferably dished, is loosely engaged on the two latter pivots.

In order to stabilize or balance the device I pivot two bars or links 22 to the opposite sides of either block 11, 12, but preferably to the block 12 since the thrust bearing 15 on the fitting 14 engages said block when the jack is operated to raise an object. The other ends of the bars 22 are pivoted to the links 9 at 24. Each pivot 24 is below-the longitudinal axis of the link 9. The pivots 6 and 7 are below the longitudinal axes of the links 8 and 9 respectively.

By rotating the screw 13 in the proper direction the block 11 is caused to travel toward the other block, the lower crossing links pivoting on their lower pivots and forcing the blocks and the screw upwardly. At the same time the upper crossing links pivot on the blocks and their upper ends rise as they move toward each other under the influence of the moving blocks. The plate and the object thereon are therefore raised to the desired height or to that for which the jack is designed.

The bars 22 afford additional leverage and effectively balance the device so that it will not tip over when operated and the off center pivotal points and the slots or depressions in the base permit the device to be collapsed to an exceedingly low point-about 3 inches high.

In Fig. 4 I illustrate the upper links 25 as having their upper ends curved downwardly somewhat. This feature accomplishes a further slight gain in reduction in height of the collapsed jack.

As shown in Fig. 5 I may omit the pivot 18 in the upper links 16, 1'7 and pivot their upper ends to a channel or other support 26. The bars 2'7, similar to the bars 22, are pivoted to the block 11 and to the links 1'7 to further stabilize the device. In this modification the upper ends of the links 16, 17 do not change their relative positions since they are pivoted to the support 26, and some additional power is thereby gained.

What I claim is:

1. A jack comprising a base, two pairs of crossing links pivoted below their longitudinal axes at their lower ends to the base, a screw, two blocks mounted on the screw and pivotally connected to the pairs of crossing links respectively, stabilizing members pivotally connected to one of the blocks and to a pair of said links, a support and crossing links pivoted to the blocks and engaging the support.

2. A jack comprising a base, two pairs of cross-, ing links pivoted below their longitudinal axes at their lower ends to the base, means in the base to receive the lower extremities oi the links, a screw, two blocks mounted on the screw and pivotally connected to the pairs of crossing links respectively, one of the blocks being internally threaded, stabilizing members pivotally connected to one of the blocks and to a pair of said links, a support and crossing links pivoted to the blocks and engaging the support.

3. A jack comprising a base, two pairs of crossing links pivoted below their longitudinal axes at their lower ends to the base, a screw, an internally threaded block mounted on the screw; a loose block on the screw, the blocks being pivotally connected to the pairs of crossing links respectively, stabilizing members pivotally connected to one of the blocks and pivoted to a pair of said links at points below the longitudinal axes thereof, a support and crossing links pivoted to the blocks and engaging the support.

4. A Jack comprising a base, two pairs or crossing links pivoted below their longitudinal axes at their lower ends to the base, means in the base to receive the lower extremities of the links,,a screw, blocks on the screw and pivotally connected to the pairs of crossing links respectively one of the blocks being adapted to travel on the screw, stabilizing members pivotally connected to one of the blocks and pivoted below their longitudinal axes to a pair of said links, a support and crossing links pivoted to the blocks and engaging the support.

5. A lifting jack comprising a base, two pairs of crossing links pivoted at their lower ends to the base, a screw, blocks on the screw pivotally connected to the upper ends 01' the pairs of links respectively one of the blocks being adapted to travel on the screw, two pairs of crossing links pivotally mounted at one end on the blocks respectively, a support engaging the opposite ends of the latter links and two pairs of stabilizing links pivoted to the blocks respectively, one of said pairs of stabilizing links being also pivoted to one of the support engaging pairs of links and the other pair of stabilizing links being also pivoted to one of the base supported pairs of links.

EARL W. CONRAD. 

